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1.8x Corrected Barlow for Dream Astrographs |
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The illumination chart above shows that illumination
is still extremely high, very close to 90%, at the edge of a
24mm x 36mm CCD chip. |
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The left square box is 100 microns on a side. The
right box is 50 microns per side. |
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The left spot diagram represents a star's shape for
a f8 Ritchey-Chretien Cassegrain at the extreme corner of a 24mm
x 36mm CCD chip. |
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The right spot diagram represents a star's shape for
the 1.8x Corrected Barlow on a Dream Astrograph (f6.7 using the
corrected barlow) at the same location, the corner of a 24mm
x 36mm CCD chip. |
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The RMS Radius for the R-C Cassegrain and corrected
barlow Dream Astrograph are 22 and 17 microns respectively. |
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The barlow has a back focus distance, from the last
lens element to the focal plane, of 182mm. This allows ample
room for Adaptive Optics units and/or off-axis guiders. The latter
allows for guiding prior to a filter. This is highly advantageous
for narrowband work. |
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To see spot diagrams of the corrected Dream Astrograph
using the standard corrector, click
here. |
